710 



SCIENCE 



[N. S. Vol. XXVII. No. ( 



chemico-physical or physiological ones. It is 

 also obvious that to demonstrate the com- 

 plexity and difficulty of a field of work is not 

 an achievement to be compared in value with 

 the demonstration that this field is simple and 

 easily explicable on a few known principles. 

 I am imder no illusion in regard to this. The 

 clear-cut, narrow tropism theory would be of 

 infinitely greater value for predicting and 

 controlling the behavior of animals than any- 

 thing I have offered, if only it were true. 

 I am sure I regret that I can make no attempt 

 to put an equally simple schema in place of 

 the one I criticized; if the phenomena of be- 

 havior were of elemental simplicity, that 

 would certainly be much more convenient, 

 though perhaps they would then be less inter- 

 ■€sting. Many of the concepts used in my 

 analysis — " physiological states," " selection," 

 " trial and error," and the like — are collective 

 ones, characterizing varied phenomena of a 

 high degree of complexity. They all require 

 much further analysis; they are programs for 

 future work, not final solutions of the prob- 

 lems. My analysis was mainly an attempt to 

 lay out the field, to point out the principal 

 phenomena with which we have to deal, and 

 to define some of the main problems. If any 

 one attempts to explain all behavior on any 

 one basis, to unlock all its secrets by any 

 catchword whatever, be it "trial and error," 

 " selection," " tropisms " or what not, he lacks 

 a realization of the complexity of his field of 

 investigation. Like other complex fields, that 

 of behavior, even in lower organisms, must be 

 divided up; the various factors must be sub- 

 jected to long and intense special investiga- 

 tion, with a realization that we have here 

 material for the work of many generations 

 of investigators. H. S. Jennings 



Johns Hopkins Univeesitt, 

 Baltimoke, Md., 

 November 26, 1907 



physical properties of the mineral the reader 

 is referred to the original article.'^ The an- 

 alysis of the mineral, made by W. C. Blasdale, 

 showed the following: 



SPECIAL ARTICLES 



INTEEPRETATION OF THE CHEMICAL COMPOSITION 

 OF THE MINERAL BENITOITE 



In July, 1907, Professor G. D. Louderback 

 published an interesting paper on the new 

 mineral benitoite. For a description of the 



I 



This yields the empirical formula BaTiSijOj. 

 From this Louderback concludes : " Benitoite 

 is then a very acid titano-silicate of barium 

 and stands in a class by itself, both as regards 

 acid silicates and titano-silicates." 



Upon reading the paper, immediately 

 after its publication last year, I noticed that 

 there was a very striking similarity to be 

 observed between the composition of benitoite 

 and beryl, for, if benitoite be interpreted as a 



inetasilicate, we have: 



II III 



Beryl BejAl.lSiOjJa 



II IV 

 Benitoite Ba.Tij ( SiOa) ». 



This similarity in the chemical composition 

 is sufficient to consider the two compounds as 

 isomorphous, for, although titanium with a 

 valency of four replaces aluminium with one 

 of three, the total valences in both compounds 

 are the same. There is, however, a difference 

 of one with respect to the number of atoms. 

 A few examples of well-known isomorphous 

 series will show that the above is not unusual. 



In the marcasite group we have: 



II li 

 Marcasite FeS S 



mil 

 Arsenopyrite FeAsS 



III III 

 Lollingite FeAsAs. 



Here the number of atoms is constant in all 

 three compounds, but the valences vary. The 

 albite-anorthite group furnishes another illus- 

 tration. 



I III IV 

 Albite NaAlSiSi.Os 



' " Benitoite, a New California Gem Mineral," 

 University of California Publications, Bulletin 

 of the Department of Geology, Vol. 5, 149-153, 

 1907. 



